Adaptive pal field comber

ABSTRACT

A video decoder includes an adaptive comber to generate a combed video image, and the adaptive comber selectively combs using 2D combing, frame combing, and field combing.

FIELD OF THE INVENTION

The present invention relates to an adaptive phase alternating linefield comber based video decoder. The invention further relates to butis not limited to an adaptive phase alternating line field comber aspart of a television receiver.

BACKGROUND OF THE INVENTION

Analogue video are video signals wherein the image information is storedby analogue modulation on an electrical signal. There are manyestablished color analogue video formats. Such color analogue videosystem specifies the video image in terms of the luminance or luma (Y)and chrominance or chroma (C) of the image. An analogue video decodercan receive in a single channel or signal a color analogue encoder videosignal for example from a composite video input or from a televisionbroadcast encoded analogue signal. The luma and chroma components of theanalogue video signal can then be separated in such a way that they canthen be output to a screen or display.

Analogue video is used in both consumer and professional applicationsand is found in many terrestrial television broadcast systems. Forexample, composite video, a format of analogue television picture(picture only) signals contain all the required video informationincluding color in a single signal. Composite video is sometimes knownas CVBS (composite video baseband signal). Composite video signals canbe found, for example, in many standard formats such as NTSC (NationalTelevision System Committee), PAL (Phase Alternating Line), and SECAM(Sequential Color with Memory) as well as the various sub-standards ofthese standards such as PAL-M, PAL-N, NTSC443, PAL-60. The compositesignal is a composite of three source signals Y (luma), U and V(representing hue and saturation or chrominance). The typical analoguevideo decoder receives such a composite video signal and separates theseinto the three source signals. However in order to apply correct colordecoding techniques to separate the luma and chroma to produce thecorrect image on the final output screens, it is important to detect thecorrect mode or standard applied.

For PAL video decoding, in order to improve the luma/chroma separation,additional processing of the CVBS signals can be carried out. Forexample a process of 2D (spatial filtering) decoding and 3D (temporal,the inter frame or field comb filtering) decoding can be performed toattempt to improve the image quality. Performing field combing basedonly on motion detection can generate field motion artifacts due tofield motion in phase subcarriers taps being spatially displaced.

SUMMARY OF THE INVENTION

Embodiments of the present application aim to address the aboveproblems.

There is provided according to the disclosure a video decodercomprising: an adaptive comber configured to generate combed videoimage, wherein the adaptive comber is configured to selectively combusing at least one of: 2D combing, frame combing, and field combing.

In such embodiments the video decoder can thus comprise an adaptive combblock comprising adaptive 2D combing, adaptive frame combing, and anadaptive field combing and being based on (chroma luma determination)CLD, field motion and Vlogic (vertical correlation) status.

Furthermore in such embodiments the adaptive comb block can beconfigured to do frame combing when detecting no field motion, elsebased on the levels of field motion, CLD and vlogic status perform fieldcombing or 2D combing.

The video decoder may further comprise an adaptive comb controllerconfigured to generate at least one control signal for the adaptivecomber to select from the at least one of: 2D combing, frame combing,and field combing.

The adaptive comb controller may comprise at least one of: a chroma-lumastatus determiner, a vertical image correlator, and a spatio-temporalimage correlator.

The adaptive comb controller may comprise a controller logic configuredto generate at least one control signal dependent on the output of theat least one of: chroma-luma status determiner, vertical imagecorrelator, and spatio-temporal image correlator.

The adaptive comber may comprise at least two of: a 2D comber, a framecomber, and a field comber, and the adaptive comb further may compriseat least one blender configured to receive signals from the at least twoof: the 2D comber, frame comber, and field comber wherein the at leastone blender is configured to selectively combine the received signalsdependent on the at least one control signal.

The adaptive comber may comprise the frame comber, wherein the framecomber is configured to be enabled for a region dependent on thespatio-temporal image correlator determining a field motion value lessthan a determined value.

The adaptive comber may comprise the field comber, wherein the fieldcomber is configured to be enabled for a region dependent on thespatio-temporal image correlator determining the region has a fieldmotion value less than a further determined value, and the chroma-lumastatus determiner determining the region does not have a chromasignature and the vertical image correlator determining that the regionhas vertical correlation less than a determined correlation threshold.

The adaptive comber may comprise the 2D comber, wherein the 2D comber isconfigured to be enabled for a region dependent on the spatio-temporalimage correlator determining the region has a field motion value greaterthan a further determined value and the vertical image correlatordetermining that the region has vertical line correlation greater than adetermined correlation threshold.

The adaptive comber may be configured to adaptively perform differentcombing operations on the same image.

The adaptive comber may comprise a tap selector configured to selectpicture elements to comb.

The tap selector may be configured to select picture elements to combdependent on a combination of: a chroma-luma status value of the imagesignal, a vertical image correlation value of the image, and aspatio-temporal image correlation value.

The adaptive comber may comprise a tap blender configured to blendfilter elements selected dependent on a combination of: a chroma-lumastatus value of the image signal; a vertical image correlation value ofthe image; and a spatio-temporal image correlation value.

The tap selector may be configured to select: a first picture signalelement, an in-phase picture signal element one frame away from thepicture signal element, and an out-of-phase picture signal element fromthe adjacent field picture signal, for field combing dependent on atleast the chroma-luma status value of the image indicating the imagesignal does not have a chroma sub carrier signature.

A television receiver may comprise the video decoder as discussedherein.

An integrated circuit may comprise the video decoder as discussedherein.

A video player may comprise the video decoder as discussed herein.

A chipset may comprise the video decoder as discussed herein.

According to a second aspect there is provided a method for videodecoding comprising adaptively combing a video signal, wherein theadaptive combing comprises selectively combing using at least one of: 2Dcombing, frame combing, and field combing.

The method may further comprise: generating at least one control signalto selectively comb using the at least one of: 2D combing, framecombing, and field combing.

Generating at least one control signal may comprise generating the atleast one control signal dependent on determining a chroma-luma statusof the video signal.

Generating at least one control signal may comprise generating the atleast one control signal dependent on determining a vertical imagecorrelation value of the video signal.

Generating at least one control signal may comprise generating the atleast one control signal dependent on determining a spatio-temporalimage correlation value.

Adaptively combing a video signal may comprise: performing at least twoof: 2D combing, frame combing, and field combing; and selectivelycombining an output from the at least two of: 2D combing, frame combing,and field combing dependent on the at least one control signal.

Adaptively combing may comprise enabling frame combing dependent ondetermining a field motion value less than a determined value.

Adaptively combing may comprise enabling field combing for a regiondependent on determining the region has a field motion value less than afurther determined value, determining the region does not have a chromasignature, and determining that the region has vertical correlation lessthan a determined correlation threshold.

Adaptively combing may comprise enabling 2D combing for a regiondependent on determining the region has a field motion value greaterthan a further determined value and the region has vertical linecorrelation greater than a determined correlation threshold.

Adaptively combing may comprise performing different combing operationson the same image.

Adaptively combing may comprise selecting at least one picture elementto comb.

Selecting at least one picture element to comb may comprise selecting atleast one picture element dependent on a combination of: a chroma-lumastatus value of the image signal, a vertical image correlation value ofthe image, and a spatio-temporal image correlation value.

Adaptively combing may comprise blending combing output elementsdependent on a combination of: a chroma-luma status value of the imagesignal, a vertical image correlation value of the image, and aspatio-temporal image correlation value.

Selecting at least one picture element to comb may comprise selecting atleast: a first picture signal element, an in-phase picture signalelement one frame away from the picture signal element, and anout-of-phase picture signal element from the adjacent field picturesignal, for field combing dependent on at least the chroma-luma statusvalue of the image indicating the image signal does not have a chromasub carrier signature.

A processor-readable medium encoded with instructions that, whenexecuted by a processor, perform a method for decoding video asdiscussed herein.

An apparatus comprising at least one processor and at least one memoryincluding computer code for one or more programs, the at least onememory and the computer code configured to with the at least oneprocessor cause the apparatus to at least perform a method as discussedherein.

According to a fifth aspect there is provided a video decodercomprising: means for adaptively combing a video signal, wherein theadaptive combing comprises selectively combing using at least one of: 2Dcombing, frame combing, and field combing.

The video decoder may further comprise: means for controlling the meansfor adaptively combing the video signal to selectively comb using the atleast one of: 2D combing, frame combing, and field combing.

The means for controlling the means for adaptively combing may comprisemeans for generating at least one control signal dependent ondetermining a chroma-luma status of the video signal.

The means for controlling the means for adaptively combing may comprisemeans for generating at least one control signal dependent ondetermining a vertical image correlation value of the video signal.

The means for controlling the means for adaptively combing comprisesmeans for generating at least one control signal dependent ondetermining a spatio-temporal image correlation value.

The means for adaptively combing a video signal may comprise: at leasttwo of: means for 2D combing, means for frame combing, and means forfield combing; and means for selectively combining an output from the atleast two of: means for 2D combing, means for frame combing, and meansfor field combing dependent on the at least one control signal.

The means for controlling the means for adaptively combing may comprisemeans for enabling the means for frame combing dependent on determininga field motion value less than a determined value.

The means for controlling the means for adaptively combing may comprisemeans for enabling the means for field combing for a region dependent ondetermining the region has a field motion value less than a furtherdetermined value, determining the region does not have a chromasignature, and determining that the region has vertical correlation lessthan a determined correlation threshold.

The means for controlling the means for adaptively combing may comprisemeans for enabling the means for 2D combing for a region dependent ondetermining the region has a field motion value greater than a furtherdetermined value and the region has vertical line correlation greaterthan a determined correlation threshold.

The means for adaptively combing may comprise means for performingdifferent combing operations on the same image.

The means for adaptively combing may comprise means for selecting atleast one picture element to comb.

The means for selecting at least one picture element to comb maycomprise means for selecting at least one picture element dependent on acombination of: a chroma-luma status value of the image signal, avertical image correlation value of the image, and a spatio-temporalimage correlation value.

The means for adaptively combing may comprise means for blending combingoutput elements dependent on a combination of: a chroma-luma statusvalue of the image signal; a vertical image correlation value of theimage; and a spatio-temporal image correlation value.

The means for selecting at least one picture element to comb maycomprise means for selecting at least: a first picture signal element,an in-phase picture signal element one frame away from the picturesignal element, and an out-of-phase picture signal element from theadjacent field picture signal, for field combing dependent on at leastthe chroma-luma status value of the image indicating the image signaldoes not have a chroma sub carrier signature.

BRIEF DESCRIPTION OF THE FIGURES

For better understanding of the present application, reference will nowbe made by way of example to the accompanying drawings in which:

FIG. 1 shows schematically a system suitable for employing a videodecoder according to some embodiments of the application;

FIG. 2 shows schematically a video decoder memory client interface infurther detail according to some embodiments of the application;

FIG. 3 shows schematically an adaptive comber in further detailaccording to some embodiments of the application;

FIG. 4 shows schematically the adaptive field motion controller infurther detail according to some embodiments of the application;

FIG. 5 shows schematically an example of frame combing filter taps forthe adaptive comber according to some embodiments of the application;

FIG. 6 shows schematically an example of field combing filter taps forthe adaptive comber according to some embodiments of the application;and

FIG. 7 shows a method of operating the adaptive comber according to someembodiments of the application.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following describes in further detail suitable apparatus andpossible mechanisms for the provision of adaptive field combing.

With respect to FIG. 1 an example electronic device or apparatus 10 isshown within which embodiments of the application can be implemented.

The apparatus 10 in some embodiments comprises a receiver configured toreceive a radio frequency modulated television and/or video signal andoutput the analogue video signal to the processor 5. In some embodimentsthe receiver can be controlled by the processor to demodulate/select thechannel to be received.

The apparatus 10 in some embodiments comprises a processor 5 which canbe configured to execute various program codes. The implemented programcodes can comprise video decoding for receiving the received video dataand decoding and outputting the data to the display 7. The implementedprogram codes can be stored within a suitable memory.

In some embodiments the processor 5 can be coupled to memory 21. Thememory 21 can further comprise an instruction code section 23 suitablefor storing program codes implementable upon the processor 5.Furthermore in some embodiments the memory 21 can comprise a stored datasection 25 for storing data, for example video data. The memory 21 canbe any suitable storage means. In some embodiments the memory 21 can beimplemented as part of the processor in a system-on-chip configuration.

The apparatus 10 can further comprise a display 7. The display can beany suitable display means featuring technology for example cathode raytube (CRT), light emitting diode (LED), variably backlight liquidcrystal display (LCD) for example LED lit LCD, organic light emittingdiode (OLED), and plasma display. The display 7 can furthermore beconsidered to provide a graphical user interface (GUI) providing adialog window in which a user can implement and input how the apparatus10 displays the video. In some embodiments the apparatus can beconfigured to communicate with a display remote from the physicalapparatus by a suitable display interface, for example a High DefinitionMultimedia Interface (HDMI) or a Digital Video Interface (DVI) or beremodulated and transmitted to the display.

The apparatus 10 further can comprise a user input or user settingsinput apparatus 11. The user input can in some embodiments be a seriesof buttons, switches or adjustable elements providing an input to theprocessor 5. In some embodiments the user input 11 and display 7 can becombined as a touch sensitive surface on the display, also known as atouch screen or touch display apparatus.

Embodiments of the application attempt to perform adaptive field combingbased on information such as field motion, (Chroma/Luma Detect) CLDstatus, V logic status (in other words whether there is correlationbetween lines of the field). Thus in embodiments of the application,field combing is enabled for specific image scenarios based on thechroma/luma status (CLD) of the current and previous field pixel orblock of pixels being analyzed and the spatial/vertical correlation suchthat the field combing artifacts are reduced. In other words, wherefield combining is expected to improve image quality in the region, itcan be applied but then be disabled in other regions.

An example of a PAL comb tap arrangement is shown with respect to FIG.5. FIG. 5 shows a pixel under investigation 401 which is in Line 3 andwith phase 90°, and PAL comb points or taps across two lines above (theone line above being line 2 with phase of 0° and the two line abovebeing line 1 with phase of 270°) and below (the one line below beingline 4 with phase of 180° and the two line below being line 5 with phaseof 270°) line of the same field (Field 1) and across two frames away(Field 4) and four frames away (Field 8) in the 8^(th) field sequence.For temporal frame combing the 4 fields away tap (in other words 2 frameaway tap, as one frame consists of two fields) is because the combingtaps have to be 180 degrees out of phase, and in case of PAL the tapswhich are 4 fields away are 180 degrees out of phase. The field 8 tap is4 frames away and can in some examples be used for motion detection inframe motion processing. This is because for motion check the taps haveto be in phase and for PAL, the taps which are 4 frames away are inphase.

As can be seen in FIG. 5, so that the phases of the input to thetemporal tap values are suitable for combing; they are required to beeither “in phase” or 180 degrees out of phase and therefore the temporalcomb tap used is two frames (or four fields) away and the frame motioncheck requires “in phase” inputs and therefore requires a distance of 4frames (or 8 fields). Furthermore the filter taps in the same field asthe pixel are the two-dimensional comb filter taps for a number of linesabove and below the current line.

Thus in some embodiments an adaptive filter can be used where dependenton determining image motion then the filter can use only thetwo-dimensional combing filter configuration. These 2-D comb filters canbe configured to use five line, three line or notch filtering (where 5taps, 3 taps or a single tap respectively are used as the input to thefilter).

In some embodiments so to enable better spatial combing, the line tapsamples should be as close as possible to the current line beinganalyzed but because of field interlacing to form complete frames (andthe 2 line across comb tap configuration in PAL systems) the combingline taps are “far away” from the analyzed pixel and thus combing is notas efficient as the probability of correlation with the analyzed pixelis less.

With respect to FIG. 6, a further PAL field chroma phase diagram isshown wherein sample values for adaptive filter taps can be seen. Thefigure shows a first frame (N), and parts of Field 1 and Field 2 whichform the first frame and a second frame (N=1), parts of Field 3 whichcontain the line information spatially the same as but temporallydisplaced from Field 1. Thus as shown in FIG. 6 the first field (Field1) has line 1 with a phase of 0°, line 2 with a phase of 90° and line 3with a phase of 180°, the second field (Field 2) has line 314 (spatiallybetween lines 1 and 2 and 312 lines away from line 2 of field 1) with aphase of 270°, and line 315 (spatially between lines 2 and 3) with aphase of 0° and a third field (Field 3) with line 626 (a temporallydelayed line 1 and 624 lines away from line 2 of field 1) with a phaseof 90°, line 627 (temporally delayed spatial analogue of line 2) with aphase of 180°, and a line 628 (temporally delayed spatial analogue ofline 3) with a phase of 270°.

Furthermore spatial analogue of the lines where the samples are 180°phase apart are also shown in FIG. 6 by the “dashed” link. For example,line 2 501 (Field 1) and line 314 (Field 2) 503 are out of phase by 180°and shown as linked by line 502 and thus can be combed based oncorrelation with line 626 (Field 3) 505 linked by line 504 as line 2 501and 626 are in phase and line 314 in anti-phase.

Furthermore line 314 in Field 2 can be considered to be closestspatio-temporal scan line to line 2 temporally displaced because of theinterlaced scanning method. Therefore in some embodiments a combingoperation can be performed wherein the temporal combing taps are Line 2and Line 314 as these line taps are 180° out of phase, and the motiondetection taps are Line 2 and Line 626 as these line taps are in phase(both at 90°).

In other words a suitable combing operation can therefore be representedmathematically as: (line 2−line 314)/2 to generate a temporal chromacombing value.

Furthermore motion can be detected by generating the difference betweenline 2 and line 626, assuming that the same ‘feature’ in the imagecovers both line 2 and line 626 as will be discussed herein.

It would be understood that this diagonal relationship can be seen tooccur through the image.

With respect to the taps shown in FIG. 6 by using motion and adaptiveblends of the field comb taps in some embodiments the filtering canproduce better image quality for slow moving images as there is agreater probability of correlated field combing compared to fixed 2Dcombing.

Furthermore, adaptively field combing the embodiments of the applicationdescribed herein enables intermediate stage filtering operations betweenone-dimensional, three line or five line combing techniques (used duringimages with detected motion) and multiple frame or field combing usingthe above tap configuration (where the video images have no motion).

With respect to FIG. 2, an example of the memory client interfacebetween memory and decoder and in such examples the field and frame tapswhich can be used in embodiments of the application are shown. The videodecoder 100 can, for example be configured to process the video signalto perform motion detection and frame combing using a series of frame orfield delayed inputs. For example as shown in FIG. 2 the decoder canread picture data with a one-frame delayed input 153, a two framedelayed input 155, a three frame delayed input 157, and a four framedelayed input 159. This configuration would thus enable a temporal delayof up to 4 frames. In some embodiments the input from the memory clientto the decoder 100 can be a 10 bit read. Furthermore for field combingand field motion detection, the decoder can read picture data with afirst field tap 161 and a second field tap 163 for transferring fieldrelated data from the memory 21 to the decoder 100. Furthermore in orderto write the data and motion information, the interface can comprise adata 10 bit write 151 and a motion 6 bit write 171. Furthermore motiondata can be read from the memory 21 to the decoder by two 6 bit readbuses 173 and 175 for transferring delayed motion data for motiondetection.

With respect to FIG. 3 the adaptive comber as part of the decoder 100 isshown in further detail. In some embodiments these can comprise a 1D/2Dcomber circuit 101, configured to perform a 1D or 2D comb using anysuitable 1D or 2D combing algorithm. The output of the 1D or 2D comb ispassed in some embodiments to a first blender 107.

Furthermore in some embodiments the adaptive comber can comprise a fieldcomber 103 configured to perform field combing. It would be understoodthat any suitable field combing operation could be used such as thosedescribed herein with respect to FIG. 6 where the nearest field tap canbe a spatially adjacent but field delayed sample, taken with respect toa further spatially adjacent and field delayed sample 180 degrees out ofphase as the original tap sample. The output of the field comber 103 canbe passed to the first blender 107.

The adaptive comber can further comprise a motion controller 109. Themotion controller 109 can in some embodiments further comprise a fieldmotion logic part, CLD and V-logic control part and frame motion controlpart and will be discussed hereafter.

The motion controller can in some embodiments as shown in FIG. 4comprise a field motion detector 201 configured to receive the fields f0(Field 1), f1 (Field 2) and f2 (Field 3) to determine correlationbetween each of the fields. Furthermore the field motion detector 201can be configured to receive an input from the spatio-temporal CLD logic203.

In some embodiments the motion controller 109 comprises aspatio-temporal CLD logic block 203, also configured to receive theprevious field(s) information and configured to determine thechroma/luma status of the input video signal of the current and previousfields. The CLD logic block 203 is configured to determine the chromacharacteristics/signature. This can be done by any suitable means suchas detecting for pixels which in a chroma cycle will, for eachalternating sample, be nearly equal in magnitude but opposite in sign.Thus in some embodiments the addition of alternate samples among thefour chroma pixels would be a low value near to 0. In some embodiments achroma amplitude check can be carried out. The spatial/temporal CLDblock thus can provide CLD control information to the field motiondetector 201. This control information has spatial CLD signature statusand temporal CLD signature status for better control of the motionlogic. The spatial/temporal CLD logic part 203 can be configured tooutput the logic output to a mixer 207.

Furthermore in some embodiments the motion controller 109 comprises aV-logic or vertical correlation (VCORR) logic 205. The verticalcorrelation logic 205 can be configured to receive the line tapinformation and provide the information to a mixer 207.

The V-logic or VCORR logic 205 thus in such embodiment can be configuredto determine the degree of correlation between lines in the same fieldwhich can be used to control the 2D filtering operation where adjacentspatial lines are not similar to prevent unnecessary blurring of theimage.

In some embodiments the mixer 207 can be configured to output a mixedversion of the spatial/temporal CLD logic output and the verticalcorrelation logic 205 output to the adaptive motion controller 209.

The adaptive motion controller 209 can be configured to receive thefield motion information, the mixer information and control the blender107 and 111, the blender 111 is controlled by frame motion part ofmotion controller 109 (not shown in the diagram of 109) to output acombed output dependent on image data such as detection of motion of theframe, field, and the correlation between the vertical dimension pixelssuch that based on field motion, CLD status, V logic status, the fieldcombing is adaptively enabled when specific image regions are likely toproduce good effects when using field combing and thus prevent or reducethe generation of field combing related artifacts.

With respect to FIG. 3, there is shown a frame comber 105, the framecomber 105 can be configured to perform any suitable frame combingoperation to produce an output for the pixel/line based on thepixel/line in proceeding and/or succeeding frames and pass this outputto the blender 111.

The first blender 107 is configured to blend the outputs of the 1D/2Dcomber 101 and the field comber 103 to produce an output to the secondblender 111. The first blender output can be mathematically describedas:FBlenderOutput=input1(k)+input2(1−k),

where K (can be <=1) is the blend control signal generated from theadaptive motion control 209 and the mixer 207, and the input 1 is fromthe field comber 103 output and the input 2 is from the 1D/2D comber101.

The second blender 111 is configured, based on the frame motion controlinformation from the adaptive motion controller, to further output ablended version of the output of the first blender 107 and the framecomber 105.

With respect to FIG. 7 the operation of the adaptive comber and motioncontroller is shown in further detail.

Firstly the spatial/temporal CLD logic device 203 is configured todetermine the chroma/luma status of the current field and previousfields in question.

The determination of the chroma/luma status is shown in FIG. 7 by step701.

Furthermore the V logic or vertical correlator logic 205 can beconfigured to determine the spatial/vertical correlation across lines ofthe current field.

This operation of determining the spatial/vertical correlation acrosslines is carried out in FIG. 7 by step 703.

Furthermore the field motion detector 201 can be configured to determinewhether or not the image region in question is still or is moving over aseries of fields. In such embodiments the line taps as discussed hereinwith respect to FIGS. 5 and 6 can be used to determine field motion.

The motion detection operation is shown in FIG. 7 by step 705.

Where the image region is still or less than a determined field motionthreshold then the adaptive motion controller can output controls to theblenders such that the frame combing operation is performed.

The operation of outputting/performing frame combing is shown in FIG. 7by step 707.

However where the image is not still, or where the motion would producean artifact in frame combing, for example by being greater than thedetermined field (or frame) motion threshold then the informationprovided by the chroma/luma status determination, Vlogic determinationand field motion determination can be used to determine whether or notfield combing is possible.

The test operation of whether or not field combing is possible is shownin FIG. 7 by step 709.

Where field combing is determined to be possible because of the CLDoutput, in other words determining that the video signal signature isnot chroma (for example), the field motion output determining that themotion between adjacent fields is less than a further or seconddetermined motion threshold, and the Vlogic determination indicates thatthe adjacent field/line tap as shown in FIG. 6 is not correlated thenthe field comber 103 signal, using the field comb taps as discussedherein, is output. In other words field combing is performed.

The operation of performing field combing is shown in FIG. 7 by step711.

Where field combing is not possible, for example because of significantframe motion determination in the image, then the decoder and the motioncontroller is configured to control the output such that the output ofthe 1D and 2D combing operation is output, in other words that thedecoder performs 2D combing or 1D combing.

The performing of 1D/2D combining is shown in FIG. 7 by step 713.

Thus in embodiments having adaptive control logic, the field combing isenabled at only specific image situations, thereby having less fieldmotion artifacts and better image quality. Furthermore, in suchembodiments the image quality would be better than motion compensatedcombing.

In some embodiments there can be considered to be an adaptive comberconfigured with an adaptable tap or filter selector configured toanalyze the image element by element or region by region andselect/blend filter elements dependent on the picture element andsurrounding image region spatio, spatio-temporal and image encodingcharacteristics.

In general, the various embodiments of the invention may be implementedin hardware or special purpose circuits, software, logic or anycombination thereof. For example, some aspects may be implemented inhardware, while other aspects may be implemented in firmware or softwarewhich may be executed by a controller, microprocessor or other computingdevice, although the invention is not limited thereto. While variousaspects of the invention may be illustrated and described as blockdiagrams, flow charts, or using some other pictorial representation, itis well understood that these blocks, apparatus, systems, techniques ormethods described herein may be implemented in, as non-limitingexamples, hardware, software, firmware, special purpose circuits orlogic, general purpose hardware or controller or other computingdevices, or some combination thereof.

The embodiments of this application may be implemented by computersoftware executable by a data processor of the mobile device, such as inthe processor entity, or by hardware, or by a combination of softwareand hardware. Further in this regard it should be noted that any blocksof the logic flow as in the Figures may represent program steps, orinterconnected logic circuits, blocks and functions, or a combination ofprogram steps and logic circuits, blocks and functions. The software maybe stored on such physical media as memory chips, or memory blocksimplemented within the processor, magnetic media such as hard disk orfloppy disks, and optical media such as for example DVD and the datavariants thereof, CD.

The memory may be of any type suitable to the local technicalenvironment and may be implemented using any suitable data storagetechnology, such as semiconductor-based memory devices, magnetic memorydevices and systems, optical memory devices and systems, fixed memoryand removable memory. The data processors may be of any type suitable tothe local technical environment, and may include one or more of generalpurpose computers, special purpose computers, microprocessors, digitalsignal processors (DSPs), application specific integrated circuits(ASIC), gate level circuits and processors based on multi-core processorarchitecture, as non-limiting examples.

Embodiments of the inventions may be practiced in various componentssuch as integrated circuit modules. The design of integrated circuits isby and large a highly automated process. Complex and powerful softwaretools are available for converting a logic level design into asemiconductor circuit design ready to be etched and formed on asemiconductor substrate.

Programs, such as those provided by Synopsys, Inc. of Mountain View,Calif. and Cadence Design, of San Jose, Calif. automatically routeconductors and locate components on a semiconductor chip using wellestablished rules of design as well as libraries of pre-stored designmodules. Once the design for a semiconductor circuit has been completed,the resultant design, in a standardized electronic format (e.g., Opus,GDSII, or the like) may be transmitted to a semiconductor fabricationfacility or “fab” for fabrication.

The foregoing description has provided by way of exemplary andnon-limiting examples a full and informative description of theexemplary embodiment of this invention. However, various modificationsand adaptations may become apparent to those skilled in the relevantarts in view of the foregoing description, when read in conjunction withthe accompanying drawings and the appended claims. However, all such andsimilar modifications of the teachings of this invention will still fallwithin the scope of this invention as defined in the appended claims.

The invention claimed is:
 1. A video decoder comprising: an adaptivecomb configured to generate a combed video image from an image signal;and an adaptive comb controller comprising: at least one of a verticalimage correlator and a spatio-temporal image correlator configured togenerate an output signal representing at least one of a vertical imagecorrelation value of the image signal and a spatio-temporal imagecorrelation value of the image signal, a field motion detectorconfigured to determine a field motion value as a function of fieldmotion between adjacent fields of the combed video image and to, basedthereupon, generate the output signal representing the field motionvalue; and controller logic configured to generate a control signal tocause the adaptive comb to selectively comb using 2D combing, framecombing, or field combing based upon the output signal; wherein theadaptive comb comprises at least one blender configured to receivesignals from a frame comb and a field comb; wherein the at least oneblender is configured to selectively combine the received signalsdependent on the control signal; wherein the control signal causes theframe comb to process a region dependent on the spatio-temporal imagecorrelator determining the field motion value to be less than a firstmotion threshold value; and wherein the control signal causes the fieldcomb to process the region dependent on the spatio-temporal imagecorrelator determining the field motion value to be indicative ofmotion, to be greater than the first motion threshold value, and to beless than a second motion threshold value.
 2. The video decoder asclaimed in claim 1, wherein the adaptive comb further comprises a 2Dcomb, and wherein the at least one blender is further configured toreceive signals from the 2D comb.
 3. The video decoder as claimed inclaim 2, wherein the field comb is configured to also process the regiondependent on a chroma-luma status determiner determining the region doesnot have a chroma signature and the vertical image correlatordetermining that the region has vertical correlation less than adetermined correlation threshold.
 4. The video decoder as claimed inclaim 2, wherein the 2D comb is configured to process the regiondependent on the spatio-temporal image correlator determining the regionhas a field motion value greater than a further determined value and thevertical image correlator determining that the region has vertical linecorrelation greater than a determined correlation threshold.
 5. Thevideo decoder as claimed in claim 1, wherein the adaptive comb isconfigured to adaptively perform different combing operations on thesame image.
 6. The video decoder as claimed in claim 1, wherein theadaptive comb comprises a tap selector configured to select pictureelements to comb, and a chroma-luma status determiner.
 7. The videodecoder as claimed in claim 6, wherein the tap selector is configured toselect picture elements to comb dependent on a combination of: achroma-luma status value of the image signal, a vertical imagecorrelation value of the image, and a spatio-temporal image correlationvalue.
 8. The video decoder as claimed in claim 6, wherein the adaptivecomb comprises a tap blender configured to blend filter elementsselected dependent on a combination of: a chroma-luma status value ofthe image signal; a vertical image correlation value of the image; and aspatio-temporal image correlation value.
 9. The video decoder as claimedin claim 7, wherein the tap selector is configured to select: a firstpicture signal element, an in-phase picture signal element one frameaway from the picture signal element, and an out-of-phase picture signalelement from the adjacent field picture signal, for field combingdependent on at least the chroma-luma status value of the imageindicating the image signal does not have a chroma sub carriersignature.
 10. A television receiver comprising the video decoder asclaimed in claim
 1. 11. An integrated circuit comprising the videodecoder as claimed in claim
 1. 12. A video player comprising the videodecoder as claimed in claim
 1. 13. A chipset comprising the videodecoder as claimed in claim
 1. 14. A method of decoding video signalscomprising: determining a chroma-luma status of a video signal, avertical image correlation value of the video signal, and aspatio-temporal image correlation value and generating an output signalbased thereupon; determining a field motion value as a function of fieldmotion between adjacent fields of the combed video image and generatingthe output signal based thereupon; and selectively combing the videosignal using 2D combing, frame combing, or field combing, based upon theoutput signal; wherein selectively combing comprises processing a regionusing the frame combing dependent on the field motion value to be lessthan a first motion threshold value; and wherein selectively combingfurther comprises processing the region using the field combingdependent on the field motion value being indicative of motion, beinggreater than the first motion threshold value, and being less than asecond motion threshold value.
 15. The method as claimed in claim 14,wherein selectively combing further comprises processing the regionusing the field combing dependent on determining that the region doesnot have a chroma signature, and determining that the region hasvertical correlation less than a determined correlation threshold. 16.The method as claimed in claim 14, wherein selectively combing alsocomprises enabling 2D combing for a region dependent on determining theregion has a field motion value greater than the second motion thresholdvalue and the region having a vertical line correlation greater than adetermined correlation threshold.
 17. The method as claimed in claim 14,wherein selectively combing comprises performing different combingoperations on the same image.
 18. The method as claimed in claim 14,wherein selectively combing comprises selecting at least one pictureelement to comb.
 19. The method as claimed in claim 18, furthercomprising blending combing output elements dependent on a combinationof: a chroma-luma status value of the image signal, a vertical imagecorrelation value of the image, and a spatio-temporal image correlationvalue.
 20. The method as claimed in claims 18, wherein selecting atleast one picture element to comb comprises selecting at least: a firstpicture signal element, an in-phase picture signal element one frameaway from the picture signal element, and an out-of-phase picture signalelement from the adjacent field picture signal, for field combingdependent on at least the chroma-luma status value of the imageindicating the image signal does not have a chroma sub carriersignature.
 21. A non-transitory processor-readable medium encoded withinstructions that, when executed by a processor, perform a method fordecoding video claimed in claim
 14. 22. Apparatus comprising at leastone processor and at least one memory including computer code for one ormore programs, the at least one memory and the computer code configuredto with the at least one processor cause the apparatus to at leastperform a method as claimed in claim
 14. 23. A video decoder,comprising: an adaptive comb configured to generate a combed videoimage; and an adaptive comb controller comprising: at least one of achroma-luma status determiner, a vertical image correlator and aspatio-temporal image correlator configured to generate an output signalrepresenting a characteristic of the video image, the characteristicbeing at least one of a chroma-luma status value of the video image, avertical image correlation value of the video image, and aspatio-temporal image correlation value of the video image, a fieldmotion detector configured to determine a field motion value as afunction of field motion between adjacent fields of the combed videoimage; wherein the characteristic includes the field motion value; and acontroller configured to, depending upon the characteristic of the videoimage, determine whether 2D combing, frame combing, or field combing isto be used, and to generate a control signal to cause the adaptive combto comb using 2D combing, frame combing, or field combing based uponthat determination; wherein the adaptive comb comprises at least oneblender configured to receive signals from a frame comb and a fieldcomb; wherein the at least one blender is configured to selectivelycombine the received signals dependent on the characteristic; whereinthe controller is configured to cause the frame comb process a regiondependent on the spatio-temporal image correlator determining the fieldmotion value to be less than a first motion threshold value; and whereinthe controller is configured to cause the field comb process the regiondependent on the spatio-temporal image correlator determining the fieldmotion value to be indicative of motion, to be greater than the firstmotion threshold value, and to be less than a second motion thresholdvalue.